Using street view, you can often see "Social Security" on a building or sign.

Social Security Office Directions and Notes :

OFFICE IS LOCATED IN THE DOWNTOWN BUSINESS DISTRICT AT 300 E 3RD ST ON T HE 2ND FLOOR IN RM 204. PARKING IS AVAILABLE ACROSS THE STREET SOUTH OF THE FOB. SEE DETAILED INSTRUCTIONS FOR MORE INFORMATION.

North Platte Social Security Office Notes

Hours of Social Security offices were reduced in November, 2012.
Almost all Social Security offices in the continental US have hours
of 9:00 to noon on Wednesdays, and 9:00 to 3:00 on other weekdays.
See if you can get an appointment by phone. Fridays may be less
crowded. You can do things like signup for Medicare
online at ssa.gov.